Dielectric barrier discharge plasma devices can be used to create ozone and ionic cascades. The plasma devices can be used in conjunction with liquid handling and transfer systems for cleaning and sterilization of the liquid delivery devices, e.g. pipette tips. Plasma discharge devices may be used to clean pipette tips on liquid handling and transfer systems that are used to transfer or otherwise manipulate liquids between two containers. Such systems are commonplace in the pharmaceutical and biotechnology industries. During the liquid handling and transfer process, the delivery devices, e.g. pipette tips, require cleaning, drying, sterilization or other such effects. These effects can be accomplished by exposure to atmospheric pressure plasma. In many instances, particularly in the pharmaceutical, biotechnology, and other research areas, the types, shapes, and sizes of the containers have been standardized.
In many systems, the pipette tips (or other object to be cleaned) are arranged in a known pattern or array, which corresponds to a similar pattern or array used for the containers. For example, the industry standardized microtitre arrays call for specific distances and spacing depending on the number of wells in a microtitre plate. Consequently, liquid handling devices use those standardized measurements to arrange their pipette tips. In turn, plasma discharge devices used to clean the pipette tips are also similarly configured. In most instances, the dielectric barriers are arranged such that they can accept the object to be cleaned (pipette tips) in their known arrangement (e.g. microtitre array). Although we focus here on the microtitre array, any pre-established arrangement can be used. For example, rather than a microtitre array, a test-tube rack of standardized dimensions and spacing could be used to determine both the spacing of the pipette tips as well as the arrangement and sizing of the plasma generating device, both itself and its components. In some arrangements, the plasma generating device occupies the same footprint as a microtitre plate that it is meant to emulate.
As is known in the art, the generation of plasma is dependent upon a number of factors, including but not limited to power input, changing the frequency, gas flow, etc. Disclosed herein are methods to optimize plasma generation such that substantially the entire gap between adjacent dielectric barriers is filled with plasma. This can be achieved by obtaining spatially disoriented plasma discharge and other types of atmospheric pressure plasmas.
The article “Research on Pattern Formation in 1D Dielectric-Barrier Discharges” by Dr. Matthew Walhout, Nov. 6, 2010 incorporated herein by reference in its entirety, describes techniques to measure the plasma discharges to allow one to determine if the plasma is disordered. The Walhout article describes a one dimensional system and analysis. It is effectively two wires that run in parallel. Walhout indicates that in his one dimensional system, spatial disorientation is achieved by overpowering the system (i.e. voltage>1250 v, see p 5/10) and in a narrow range of driving voltage (i.e. 940-980 v, see p. 5/10).
There is a need in the art to provide more methods to achieve and maintain desired plasma characteristics. Methods and systems to achieve these and other goals are disclosed herein.